Vented motor casing



Feb. 23, 1932.

C. E. BURDETTE VENIIED MOTOR CASING Filed March 18, 1929 All I INVENTOR.

71 arles B urde fie BY 117s ATTORNEY;-

10, paratus actuated thereby.

Patented Feb. 23, 1932 UNITED STATES PATENT series. I

CHARLES E. BURDETT'E, or ATHnNs, PENNSYLVANIA, AssIeNon 'IO NGnn soLn-nANn COMPANY, or JERSEY CITY, NEwJnnsEY; A CORPORATION on EW JERSEY vEN'rnn Moron CASING Application filed March 18, 1929. Serial No. 347,986.

This invention relates to pneumatic motors, and more particularly to a venting device for maintaining the atmospheric pressure within the motor casing wherein the piston or pistons of the motor reciprocate.

Another object is to utilize the pressure fluid thus conveyed from the casing as a medium for conveying lubricant to relatively movable surfaces of the motor or of the ap- Still another object is to prevent the conveyance of considerable quantities of lubricant from the casing to the atmosphere.

7 Other objects will be in part obvious and 15, in part pointed out hereinafter The figure in the accompanying drawing is an elevation partly in section of a portable grinder actuated by a pneumatic motor and having the invention applied thereto.

Referring more particularly to the draw ing, A designates generally the grinder comprising a casing B having a reduced forward extensionCto the front end of which may be secured a guard D to partly encircle the working implement, such as a grinding wheel E. To the rearward end of the casing B is secured a handle grip F whereby the machine may be guided and held to the work.

, In the form of the construction shown, the interior A of the casing B forms a reservoir for lubricant and a plurality of radially disposed cylinders G are arranged in the wall of the casing A to which they may be securedin any suitable manner. Within the cylinders G are pistons H which are connested to a crank pin J by means of connecting rods K. The crank pin J may, as shown, form an integral portion of a shaft L which extends through the reduced extension C and has secured to its front end the grinding wheel E. As a convenient means for thus securing the grinding wheel to the shaft, said shaft is shown as having a threaded end 0 for the reception of a nut P which bears against a flange Q interposed between the nut P and the grinding wheel E.

The pressure fluid for actuating the motor may be introduced into the handle grip F, as for instance, at a boss indicated by R, and its admission into the motor may be controlled by a throttle valve (not shown) adapt- 1 ed to be actuated by a trigger S. Such pressure fluid then passes through a passage T in the casing B to a valve chamber U wherein is disposed a distributing valve V of a well known type and illustrated in this instance as forming an integral portion of the shaft L.

shaft whereby it is rotated.

Preferably the element forming the valve chamber consists of a bushing W disposed in the extension C and forms: a bearing for the I shaft. I i

From the valve chamber U to the cylinders G lead supply passages X, only one of which is shown, and these supply passages also serve to return the exhaust fluid from the cylinders to the valve chamber through which it flows to an exhaust port Y in the extension C and the bushing W. Communication between the passages T and X is controlled by the valve V in a well known manner, as is also the communication between the passage X and the exhaust port Y.

The parts so far described may be of conreferred to in order to convey a clear understanding of the invention, its application and the advantages which will follow hereinafter. In devices of the type illustrated it is essential that the motor casing be vented to the atmosphere in order to prevent the upbuilding of pressure of high value in the motor casing and which pressure would otherwise act against the idle ends of the-pistons and reduce the effective force of the pressure fluid utilized for actuating the motor.

The ideal construction, of course is a cylinder and piston so machined as toentirely prevent the. leakage of pressure fluid from the cylinder past the piston into the motor casing. Such construction however'is impractical and when constructed in accordance with the usual practice some pressure fluid usually finds its way from the cylinders past the pistons intothe motor casing.

Various methods have heretofore been de vised for venting the interior of the motor casing. In certain types of motors this problem may be comparatively simple of solution .11 ventional forms and are herein only briefly but in motors such as thatillustirated where the interior of the motor casing also serves as a lubricant reservoir, the venting of the easing must be accomplished in such manner that the lubricant will not be freely expelled from the casing.

Thepresent invention aims to both provide an avenue of escape for leakage pressure fluid from the casing and also to use such leakage pressure fluid as a medium for conveying lubricant in suitable proportions and with a degree of certainty to movable parts of the machine, as for instance to the shaft and the valve. I A

The result sought is accomplished in a novel manner in the. present instance by forming a passage Z inthe shaft L with the inletopening of the passage Z at the end of said shaft and preferably on or near the axis of the shaft L adjacent the crank pin J. The opposite end of the passage Z opens into a transverse passage 6 in the shaft and said passage b in turn communicates: with a groove 0 in the bushing NV and into which the pressure fluid with the entrained lubricant flows during its passage from the casing B. A portion of such lubricant is therefore deposited in the groove 0 and will lubricate the adjacent portion of the bushing W which in this instance serves as a. bearing for the shaft L.

Preferably in the exterior of the bushing W is a passage cl whichaifords communication between the groove 0 and the forwardmost portion of the valve chamber U wherein the shaft L is journalled forwardly ofthe valveV.

Due to this arrangement the pressure fluid will flow through the passage d after passing through the groove 0 and convey lubricant to the front end of the valve chamber. However, a port 6 is formed in the bushing WVto afi'ord communication between the passage cZ and a groove f in the bushing which is in constant communication with the exhaust port Y. By means of the arrangement of the passages through the shaft and the associated elements a free path is provided for any pressure fluid which may find its way into the casing and at the same time the adequatelubrication of the shaftand such elements is assured.

By forming the passage Z as described lubricant in only minute quantities will find its way thereinto. This is dueto the fact that said passage lies close to the axis of rotation of the shaft and the valve so that when the shaft rotates rapidly the crank pin J will form'a void in the lubricant adjacent the inlet opening of the passage Z and such lubricant as will pass therethrough will be in the form of afinely reduced spray which may be readily conveyed by the pressure fluid and deposited on the bearing surfaces of the shaft. 7

I claim: 7 1. A pneumatic motor comprising a casing, a cylinder in the casing, a piston in the cylinder, a shaft, a crank pin on the shaft connected to the piston, a bearing for the shaft, and a passage in the shaft having its inlet opening adjacent the pin and its outlet opening in the periphery of the shaft through which passage pressure fluid leaking past the pistonv may be conveyed from the casing to deliver lubricant entrained by such pressure fluid to the bearing.

2. A pneumatic motor comprising a casing, a cylinder in the casing, a piston in the cylinder, a shaft, a crank pin on the shaft connected to be actuated by the piston, a valve associated with the shaft and rotated thereby. for controlling the distribution of pressure fluid to the cylinder, a bearing for the shaft and the valve, and a passage in the shaft opening from the end thereof and adjacent the crank pin for conveying pressure fluid leaking past the piston into the casing from the casing and for conveying lubricant entrained by 'such pressure fluid to spaced points in the bearing for lubricating the shaft and the valve.

3. A pneumatic motor comprising a casing having an exhaust port,'a cylinder in the casing, a piston in the cylinder, a shaft, a

crank pin on the shaft and connected to be' actuated by the piston, a valve coaxial with the shaft and rotatable therewith for controlling the admission of pressure fluid to the cylinder and the exhaust of. pressure fluid therefrom, a bearing for-the shaft and the valve, and a passage opening from the end;

of the shaft and extending through theshaft and the casing for conveying pressure fluid leaking past the piston into the casing from the casing and for conveying lubricant en'- trained by such pressure fluid to spaced points in the bearing for lubricating the shaft and the valve.

4. A pneumatic motor comprising a casing, a cylinder in thecasing, a piston in the cylinder, a shaft, a crank pin on the'shaft connected to the piston, a bearing for the shaft, a passage in the shaft having its inlet opening in the end of the shaft adjacent the crank pin and its outlet opening in the periphery of the shaft adjacent the upper end of the bearing, and a connecting passage in the bearing leading from the outlet opening to the lower end of said bearing, said connecting passage cooperating with the shaft passage for conveying pressure fluid leaking past the piston from the casing and for conveving lubricant entrained by such pressure fluid and delivering such lubricant to the upper and'lower ends of the bearing for lubrieating the shaft.

5. A pneumatic motor comprising a casing, a cylinder in the casing, a piston in the cylinder, a shaft, a crank pin on the shaft connected to the piston, a bearing for the shaft, a passage in the'shaft having its inlet opening in the end of the shaft adjacent the crank pin and its outlet opening in the periphery of the shaft adjacent the upper end of the bearing, a connecting passage in a the bearing leading from the outlet opening to the lower end of said bearing, said connecting passage cooperating with the shaft passage for conveying pressure fluid leaking past the piston from the casing and for 1 conveying lubricant entrained by such pressure fluid and delivering such lubricant to the upper and lower ends of the bearing for lubricating the shaft, and an exhaust port in the casing adjacent the lower end of the bear- 1 ing through which said pressure fluid may escape. V

In testimony whereof I have signed this specification.

CHARLES E. BURDETTE. 

